Laura has also got a group of local mums, calling themselves Mums On A Mission for Marrow.

"We are reaching out, every single person in the public can help. If they are too old to donate they can still donate blood," she said.

"It has been absolutely amazing. We have not got a match yet, but right from the start we said it was about finding a match and about raising awareness and we have definitely done that. We would love to personally thank everyone. The Welsh has a nation has been supportive."

Hollie's parents, Laura and Stephen, launched the #pantsonyourhead campaign to encourage people to join the Anthony Nolan bone marrow register.

And since they launched the campaign on June 12, Anthony Nolan has seen a 2,580% increase in the number of people joining the register in Wales, when compared to the same time period last year.

Karen Archer, Regional Register Development Manager at Anthony Nolan said: “The ‘pants on your head selfie’ idea has really taken off and is making a big difference in terms of the numbers joining the register.

“The support of sportspeople like Sam Warburton is particularly invaluable in helping us reach young men, which is really important as they are most likely to be chosen to donate but only represent 14% of the register.”

Mrs Clark said the diagnosis was "an absolute shock".

She said: “It is literally the worst thing as a parent you could be told.

“It was hard to believe because she’d been so active at the time - she loves swimming and cycling and playing with her friends, and she’d been doing all these things without us even knowing that her haemoglobin levels were dangerously low.”

The idea for the #pantsonyourhead campaign began a few weeks ago when Hollie was in a hospital bed, after receiving her first treatment.

Mrs Clark explained: “Hollie was feeling really unwell after her first round of blood transfusions, and at this time, the only way some of our family could communicate with her was by using FaceTime.

“Her uncle, Matthew, put his underwear on his head to make her laugh while he was talking to her on FaceTime and it sparked an idea for a way we could raise awareness about Anthony Nolan in a way that’s fun and personal to Hollie.”

Mrs Clark describes Hollie as a ‘typical eight-year-old, who loves everything’, from reading her favourite books to the latest girly craze of wearing ‘loom bands’.

Hollie is still managing to attend school most days, but is now surviving on blood transfusions until a suitable donor can be found on the Anthony Nolan register.

“We are keen to find a donor while Hollie remains quite stable, we do not want it to get to a stage where she is very ill again which will make the procedure more difficult,” said Mrs Clark.

The @HelpHollie #pantsonyourhead campaign has already taken off on Twitter and Facebook. The Anthony Nolan Trust are holding a donation day at the Wales Millennium Centre on Saturday, July 6, between 11am and 4pm.

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